About Us: Seminars

Fall 2008 Seminars

Seminars
are held on Tuesdays, 3:45-4:45pm in SB110, unless otherwise noted. Meet
at 3:30 in SB157 for refreshments (refreshments are available even on
Tuesdays with no seminar!). See Calvin's
Visitor Resources for maps and directions to the Science Building.

September 23:Light Play Makes Light Work Students Josh Orndorff and Tom Kok with Prof. Steve Steenwyk Two Calvin students, Tom Kok (Engineering major) and Josh Orndorff (Physics major) will present work done as interns at SoundOff Signal, a local company specializing in making various light and sound signaling devices.* They worked with Prof. Steve Steenwyk and company engineers on two projects that are at the interface of applied physics and engineering.

Tom Kok will describe how he developed predictive models to allow the manufacturer to create a specific color of light based on the spectral characteristics of LED light sources and colored filters.

Josh Orndorff will describe the steps taken to design and prototype a "light pipe" that would distribute light generated by an intense white light LED.

*This project was one of the first collaborations with a local manufacturer fostered by the Calvin Enterprise Center. Professor Steenwyk will briefly describe how this came about.

October 21:Using classical physics to understand double ionization of atoms by lasersStudents Zach Smith, Katie Shomsky and Peter Plantinga with Prof. Stan HaanWe have employed ensembles of 1 million or more "classical atoms" for computer modeling of the double ionization process. Our results are in good agreement with experiment and are very helpful in understanding the dynamics of double ionization. In this talk we will consider how the dynamics of the double ionization process changes with laser wavelength, and how back-to-back (oppositely directed) electrons can be produced.

November 18:Giant Galactic GobblersStudent Luke Leisman with Prof. Deb Haarsma
One of the main puzzles of science is determining the origins of the universe–how things formed. In this project, we are studying the most massive objects in the universe, galaxy clusters. Most galaxy clusters have a single huge bright galaxy at the center of the cluster. We were looking for evidence of these Brightest Cluster Galaxies (BCGs) as active cannibals, gobbling other galaxies as the cluster slowly mashes together due to gravity. The space between the galaxies is filled with a vast cloud of hot gas that emits X-rays. Our study examined BCGs to determine how their properties are related to the properties of the gas and the cluster as a whole. This could help us explain the cooling and heating that causes the X-ray emissions, particularly in the core of the gas cloud. To do our study we imaged 22 BCGs from the REXCESS X-ray sample in red light and determined their brightness and mass using a variety of tools including flux counting, ellipse fitting, and color modeling. We found a surprisingly strong and previously undiscovered correlation between the size of the BCG and the rate of X-ray emission at the core, which may give new insight for modeling cluster formation.

November 25:Lipid Kinetics Strongly Depend on Degree of SaturationStudent Nathan Meyers with Prof. Paul Harper
Lipids in water self-assemble to form wide diversity of phases, including flat sheet lamellar phases and cylindrical hexagonal phases. Self-assembled structures of these types can be seen in other systems and used to produce, for instance, organic solar cells. Making the transition from one phase to another requires the breaking and re-assembly of lipid membranes, which makes this an ideal system for studying the physics of how cell membranes open and close in numerous cellular processes. For our experiment, we measured the kinetics of the lamellar-hexagonal phase transition as function of saturation and analyzed our results using Avrami phase transition phenomenology.

December 9:Short Stories from Opposite Ends of the Solar System: the Atmosphere of Pluto and the Color of AriadneProf. Larry Molnar
This presentation will cover two solar system topics to which observations from the Calvin-Rehoboth observatory are contributing.

Lying beyond the most distant planet, the surface of Pluto is so cold that its atmosphere is expected to literally freeze up and fall to the ground in the winter. The first spacecraft from Earth will not reach Pluto until the year 2015. But we don't need to wait until then to test the theory. Starlight refracting through the Plutonian atmosphere and captured with a network of modest telescopes is catching the story as it happens.

Ariadne orbits in the innermost portion of the asteroid belt, and is thought to be one of the biggest pieces formed in the catacylsmic collision that formed the Flora family of asteroids some 500 million years ago. Like forensic scientists working on a very cold case, we have been systematically piecing together the evidence for exactly what occurred all those years ago. Here we discuss our recent discovery of a blue spot on one side of Ariadne and how it contributes to the puzzle.